Using A(e,e p Recoil ) in Tagged EMC and SRC Studies

Transcription

1 Using A(e,e p Recoil ) in Tagged EMC and SRC Studies Shalev Gilad, Barak Schmookler, MIT Motivation: Study the observed correlation between the measured slopes f(a/d) of the EMC effect and the measured amount of Short-Range nucleonnucleon correlations f(a/d) as expressed in a 2 (A/d) Method: Using A(e,e p Recoil ) provides more details than inclusive scattering and much more statistics than triple-coincidence measurements such as A(e,e pp) and A(e,e np) All Data Presented are Preliminary!!!

2 EMC Slope 0.35 XB 0.7 Observed EMC and SRC Correlation SRC Scaling factors XB 1.4 O. Hen et al., Int. J. Mod. Phys. E. 22, (2013) O. Hen et al., Phys. Rev. C 85 (2012) L. B. Weinstein, E. Piasetzky, D. W. Higinbotham, J. Gomez, O. Hen, R. Shneor, Phys. Rev. Lett. 106 (2011)

3 Naïve Expetations When tagging SRC and EMC events with backwardsrecoiling proton, the detected proton is a member of a short-range correlated nucleon-nucleon pair Therefore: Ø Ratios of tagged SRC per nucleon should be flat with values of a 2 Ø Ratios of tagged EMC per nucleon should be flat with values of a 2

4 Exploring the Correlation Between the EMC Effect and N-N Short-Range Correlations with Tagged EMC A non-trivial correlation between DIS physics and conventional nuclear structure effect σ(a)/a]/σ(d)/2] dr(a) EMC /dx = slope of [σ(a)/a]/σ(d)/2] for 0.35 > x >0.7 A 2 (A/d) = σ(a)/a]/σ(d)/2 for x > 1.4

5 a 2 (A/ 3 He) and a 2 (A/d) For a fixed Q 2, the minimum nucleon momentum depends on xb

6 EMC Slopes: f(a/d) Dependent; Q 2 Independent

7 The CLAS Detector and Target EG2 Target Data presented do not include analysis of back-angle EM calorimeter

8 Kinematics coverage for A(e,e )

9 Isoscaler Corrections for Inclusive EMC (A/2)(1 + σ n /σ p ) (Z + (A-Z) σ n /σ p ) Acceptance corrections also applied

10 Inclusive EMC Slopes

11 Inclusive EMC Slopes - New Target Measured (0.3 < xb < 0.55) Published Slopes C/d ± 0.01 (Stat) ± Al/d ± 0.01 (Stat) ± Fe/d ± 0.01 (Stat) ± Sn (Ag)/d ± 0.03 (Stat) ± Pb (Au)/d ± 0.01 (Stat) ± Larger than published, but published slopes are not very consisted. All inclusive ratios are NOT yet corrected for radiative effects!

12 Need for Nucleon Modifiction to Describe EMC known nuclear effects explain some of the effect, up to x B 0.5. Nuclear Binding and Fermi motion, Pions, Coulomb Field. No modification of bound nucleon structure. Kulagin and Petti

13 Kinematics coverage for A(e,e p Recoil ) Before Θ pq cut After Θ pq cuts

14 Normalized A(e,e p Recoil )/ 12 C(e,e p Recoil ) Yield Per Nucleon

15 Normalized A(e,e p Recoil )/ 12 C(e,e p Recoil ) Yield Per Nucleon

16 Why Cut on Θpq > 110 Degrees? Θpq > 107 deg Θpq < 107 deg A. V. Klimenko et al., Phys. Rev. C73, (2006) Our data

17 Nucleon Multiplicity for Θpq > 110 Degrees?

18 Solid Ratios for 70 < Θpq < 90 Degrees

19 Solid Ratios for 100 < Θpq < 120 Degrees

20 Normalized p Recoil Momentum Distributions of All Nuclei

21 Per Nucleon Normalized x-section Ratios to Deuterium VMC calculations by Argon group Arbitrarily scaled

22 Per Nucleon Normalized x-section Ratios to Deuterium

23 Isoscaler Corrections for Tagged EMC Isoscaler correction assumes the detected recoil proton originates from an SRC pair, and that the pair fraction is 5% pp, 5% nn, and 90% pp: ((0.1) Z σ p + (0.9)(A-Z) σ n ) / A ) = (A/2) (σ n /σ p ) ( 1 / ((0.1) Z + (0.9)(A-Z) σ n /σ p ) )

24 What Corrections are Still in Progress? Ø Include dependence of pp/pn ratios on recoiling proton momenta in isoscaler corrections (different/stronger than pp/p see Jan s talk on Monday). Ø This will flatten the ratios. Will it be sufficient? Ø Radiative corrections Data from CLAS data mining and Hall A Ø Transparency correction

25 SRC (Quasielastic) Inclusive and A(e,e p Recoil ) Ratios CLAS Data mining Barak Schmookler

26 SRC: 4 He(e,e p recoil ) Measurement, Hall A HRS HRS Explore studying SRC by measuring 4 He(e,e p recoil ) Optimized kinematics: p q p Q x B 1.2 Semi anti-parallel kinematics e 20.3 n array n e Big Bite Lead wall

27 SRC (Quasielastic) Inclusive and (e,e p Recoil ) Ratios

28 Summary and Questions Ø Measured Ratios of normalized yields per nucleon in (e,e ) and tagged by a backwards-recoiling proton (e,e p Recoil ) Ø Measurements done in DIS kinematics ( tagged EMC) and in quasielastics kinematics (SRC) Ø We expected tagged ratios to be flat and with values of a 2 Ø Quasielastic ratios measured to deuterium; Hall A ratios seem to follow a 2 Ø DIS ratios measured to 12 C and to deuterium as functions of p Recoil momenta and of x B Ø Ratios to 12 C seem to be flat, but significantly larger than a 2 ; seem to follow A~ 0.38

29 Summary and Questions (Cont.) Ø Ratios to deuterium are also larger than a 2 Ø Awaiting final corrections to see whether ratios as a function of p Recoil momenta are completely flat. Questions: Ø Why such large ratios for the tagged EMC)? Ø Is it 0.5 of EMC effect x 5 (20% of nucleons are SRC) ~ 2.5xa 2? Ø Given the power law (~A 0.38 ), can the ratios be explained? Ø What is the role of FSI in the large ratios Ø Any other thoughts/suggestions?